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Commit ac492e18 authored by Cary Clark's avatar Cary Clark
Browse files

tweak snap scroll 

WebView.mHeldMotionless should only be set to MOTIONLESS_FALSE
if some scrolling occurs, even in the case where motion is discarded
by snap-scroll mode.

Refactoring the code allows the code to be smaller, and provides
a single point where scrollBy() is called while dragging.

This doesn't change the snap-scroll logic in any way.

related to http://b/issue?id=2092446
parent 5af4cf47

core/java/android/webkit/WebView.java

+32 −45
Original line number Diff line number Diff line
@@ -543,11 +543,10 @@ public class WebView extends AbsoluteLayout 
    private boolean mUserScroll = false;



    private int mSnapScrollMode = SNAP_NONE;

    private static final int SNAP_NONE = 1;

    private static final int SNAP_X = 2;

    private static final int SNAP_Y = 3;

    private static final int SNAP_X_LOCK = 4;

    private static final int SNAP_Y_LOCK = 5;

    private static final int SNAP_NONE = 0;

    private static final int SNAP_LOCK = 1; // not a separate state

    private static final int SNAP_X = 2; // may be combined with SNAP_LOCK

    private static final int SNAP_Y = 4; // may be combined with SNAP_LOCK

    private boolean mSnapPositive;



    // Used to match key downs and key ups
@@ -3914,11 +3913,6 @@ public class WebView extends AbsoluteLayout 
                if (Math.abs(fDeltaX) < 1.0f && Math.abs(fDeltaY) < 1.0f) {

                    keepScrollBarsVisible = done = true;

                } else {

                    if (mHeldMotionless != MOTIONLESS_FALSE) {

                        mPrivateHandler.removeMessages(DRAG_HELD_MOTIONLESS);

                        mPrivateHandler.removeMessages(AWAKEN_SCROLL_BARS);

                        mHeldMotionless = MOTIONLESS_FALSE;

                    }

                    if (mSnapScrollMode == SNAP_X || mSnapScrollMode == SNAP_Y) {

                        int ax = Math.abs(deltaX);

                        int ay = Math.abs(deltaY);
@@ -3929,55 +3923,48 @@ public class WebView extends AbsoluteLayout 
                                mSnapScrollMode = SNAP_NONE;

                            }

                            // reverse direction means lock in the snap mode

                            if ((ax > MAX_SLOPE_FOR_DIAG * ay) &&

                                    ((mSnapPositive &&

                                    deltaX < -mMinLockSnapReverseDistance)

                                    || (!mSnapPositive &&

                                    deltaX > mMinLockSnapReverseDistance))) {

                                mSnapScrollMode = SNAP_X_LOCK;

                            if (ax > MAX_SLOPE_FOR_DIAG * ay &&

                                    (mSnapPositive

                                    ? deltaX < -mMinLockSnapReverseDistance

                                    : deltaX > mMinLockSnapReverseDistance)) {

                                mSnapScrollMode |= SNAP_LOCK;

                            }

                        } else {

                            // radical change means getting out of snap mode

                            if ((ax > MAX_SLOPE_FOR_DIAG * ay)

                            if (ax > MAX_SLOPE_FOR_DIAG * ay

                                    && ax > MIN_BREAK_SNAP_CROSS_DISTANCE) {

                                mSnapScrollMode = SNAP_NONE;

                            }

                            // reverse direction means lock in the snap mode

                            if ((ay > MAX_SLOPE_FOR_DIAG * ax) &&

                                    ((mSnapPositive &&

                                    deltaY < -mMinLockSnapReverseDistance)

                                    || (!mSnapPositive &&

                                    deltaY > mMinLockSnapReverseDistance))) {

                                mSnapScrollMode = SNAP_Y_LOCK;

                            if (ay > MAX_SLOPE_FOR_DIAG * ax &&

                                    (mSnapPositive

                                    ? deltaY < -mMinLockSnapReverseDistance

                                    : deltaY > mMinLockSnapReverseDistance)) {

                                mSnapScrollMode |= SNAP_LOCK;

                            }

                        }

                    }



                    if (mSnapScrollMode == SNAP_X

                            || mSnapScrollMode == SNAP_X_LOCK) {

                        if (deltaX == 0) {

                            // keep the scrollbar on the screen even there is no

                            // scroll

                            keepScrollBarsVisible = true;

                    if (mSnapScrollMode != SNAP_NONE) {

                        if ((mSnapScrollMode & SNAP_X) == SNAP_X) {

                            deltaY = 0;

                        } else {

                            scrollBy(deltaX, 0);

                            deltaX = 0;

                        }

                        mLastTouchX = x;

                    } else if (mSnapScrollMode == SNAP_Y

                            || mSnapScrollMode == SNAP_Y_LOCK) {

                        if (deltaY == 0) {

                            // keep the scrollbar on the screen even there is no

                            // scroll

                            keepScrollBarsVisible = true;

                        } else {

                            scrollBy(0, deltaY);

                    }

                        mLastTouchY = y;

                    } else {

                    if ((deltaX | deltaY) != 0) {

                        scrollBy(deltaX, deltaY);

                        if (deltaX != 0) {

                            mLastTouchX = x;

                        }

                        if (deltaY != 0) {

                            mLastTouchY = y;

                        }

                        mHeldMotionless = MOTIONLESS_FALSE;

                    } else {

                        // keep the scrollbar on the screen even there is no

                        // scroll

                        keepScrollBarsVisible = true;

                    }

                    mLastTouchTime = eventTime;

                    mUserScroll = true;

                }
@@ -4412,7 +4399,7 @@ public class WebView extends AbsoluteLayout 
        int vy = (int) mVelocityTracker.getYVelocity();



        if (mSnapScrollMode != SNAP_NONE) {

            if (mSnapScrollMode == SNAP_X || mSnapScrollMode == SNAP_X_LOCK) {

            if ((mSnapScrollMode & SNAP_X) == SNAP_X) {

                vy = 0;

            } else {

                vx = 0;